Gas sensing behavior and adsorption mechanism on χ3 borophene surface

• Adsorption of pollutant gases on pristine χ3 borophene computationally was studied. • Transferred charge is consistent with energy gap between band alignments of species. • Transmission coefficient and work function show a proper decrease by gas adsorption. • Surface capacity for gases evaluated in ambient temperature by CPMD simulation. Following the demands to find high sensitivity sensors for pollutant gases with compact size, we investigate the adsorption mechanism and detecting capability of χ3 borophene, based on the density functional theory (DFT) calculations. Except for HCN, the overall structure of adsorbed molecules is maintained during the adsorption on the χ3 borophene surface. The obtained adsorption energies vary from −0.20 to −2.45 eV. While the CO 2 molecule has a weak interaction with the surface, other molecules, notably CO, NO, NO 2 , SO, SO 2 , and SO 3 adsorb strongly to the surface. The minimum-energy path and energy barrier for dissociation of the HCN molecule on the surface were studied in detail through the CI-NEB method. Plots of charge density difference and electron localization function demonstrated the covalent character of the formed bonds between N or S-containing gases and the surface. Our investigations of surface and adsorbate band alignments clearly justify the amount of charge transfer in the gap between the Fermi level of χ3 borophene and the LUMO of gas molecules. Furthermore, the surface sensitivity to adsorption was confirmed by analyzing the changes in the transmission coefficient, calculated with the non-equilibrium Green’s function approach. In terms of recovery time, SO, SO 3 , and NO 2 molecules diminish the surface sensing performance, but the χ3 borophene surface is suitable for their removal from the environment. Accordingly, the thermal stability and adsorption capacity of these gases was investigated by Car-Parrinello molecular dynamics simulations. Our study not only clarifies the mechanism of the adsorption of various gas molecules on the χ3 borophene surface, but also reveals the benefit of χ3 in the sensing and removal of these gas species.